信息处理技术

Chapter 9: Information Systems Analysis and Design Chapter 1: Computer, Internet, Web, and E-Mail Basics Chapter 4: File Management, Virus Protection, and Backup 1 1 1 1

Chapter 9 Preview After this chapter, you should be able to: Describe how information systems help organizations fulfill their missions, deal with threats, and take advantage of opportunities Contrast and compare the characteristics of transaction processing systems, management information systems, decision support systems, and expert systems Apply the PIECES framework to classify problems that reduce the effectiveness of an information system Chapter 9: Information Systems Analysis and Design

Chapter 9 Preview Describe various models for the system development life cycle (SDLC), and explain the focus of the structured, information engineering, object-oriented, and rapid application development approaches to system development List the activities that take place in each phase of the system development life cycle Describe alternative hardware and software solutions that a project team might consider Chapter 9: Information Systems Analysis and Design

Chapter 9 Preview Explain the differences between unit testing, integration testing, system testing, and acceptance testing Describe the advantages and disadvantages of direct, parallel, phased, and pilot conversion techniques Explain how user feedback helps system operators identify and fix “bugs” Chapter 9: Information Systems Analysis and Design

Chapter 9 Outline Section A Section B Section C Section D Information Systems Section B System Analysis Section C System Design Section D Implementation and Maintenance Chapter 9: Information Systems Analysis and Design

Chapter 9 Information Systems Analysis and Design Section A: Information Systems 信息系统 Computer Concepts 8th Edition

Information Systems in Organizations: What is an information system? Collects, stores, and processes data to provide useful, accurate, and timely information The term “information system” always refers to a system that uses computers, and usually includes communications networks Chapter 9: Information Systems Analysis and Design Page 462

Who uses information systems? Used by the people in an organization and its customers Not everyone in an organization uses an information system in the same way An organizational chart depicts the hierarchy of employees in an organization Workers are the people who carry out the organization’s mission Managers determine organizational goals and plan how to achieve those goals Chapter 9: Information Systems Analysis and Design Page 463

Who uses information systems? Strategic Planning - The emphasis on long-range and future goals Tactical Planning - Setting incremental goals that can be achieved in a year or less Operational Planning - Scheduling employees, ordering supplies, and other activities that make day-to-day operations run smoothly Chapter 9: Information Systems Analysis and Design Page 463

How do information systems help the people in an organization? By automating routine tasks Help people make decisions in response to problems All problems are not alike, but they can be classified into three types: Structured – routine problem Semi-structured – less routine than structured problem Unstructured – requires human intuition Chapter 9: Information Systems Analysis and Design Page 464

Can an information system solve all three types of problems? An information system’s ability to assist with problem solving and decision making depends on the data that it collects and then makes available Internal information External information Chapter 9: Information Systems Analysis and Design Page 465

Do organizations require different kinds of information systems? Organizations have different missions, face different threats, and encounter different opportunities They require different kinds of information systems Chapter 9: Information Systems Analysis and Design Page 465

What is a transaction processing system? Provides a way to collect, process, store, display, modify, or cancel transactions Early transaction processing systems used batch processing to collect and hold a group of transactions for processing until the end of a day or pay period Most modern transaction processing systems use online processing. Such systems are often referred to as OLTP Commit or Rollback Chapter 9: Information Systems Analysis and Design Page 465

What is a transaction processing system? Chapter 9: Information Systems Analysis and Design Page 466

Management Information Systems: What is a management information system? Refers to a type of information system that uses the data collected by a transaction processing system Manipulates that data to create reports that managers can use to make routine business decisions in response to structured problems Chapter 9: Information Systems Analysis and Design Page 467

What is a management information system? Chapter 9: Information Systems Analysis and Design Page 467

What is a management information system? One of the major goals of an MIS is to increase the efficiency of managerial activity A summary report combines or groups data and often shows totals An ad hoc report is a customized report, generated to supply specific information not available in scheduled reports An exception report contains information that is outside of normal or acceptable ranges Scheduled reports follow a fixed format and are produced according to a preset timetable Chapter 9: Information Systems Analysis and Design Page 467

Decision Support Systems: What is a DSS? Helps people make decisions by directly manipulating data, analyzing data from external sources, generating statistical projections, and creating data models of various scenarios An executive information system (EIS) Type of DSS Provides senior managers with information relevant to strategic management activities Chapter 9: Information Systems Analysis and Design Page 468

What’s a decision support system? A DSS does not make decisions A decision model is a numerical representation of a realistic situation A decision query is a question or set of instructions describing data that must be gathered to make a decision A DSS typically includes modeling tools so managers can create a numerical representation of a situation and explore “what-if” alternatives Chapter 9: Information Systems Analysis and Design Page 468

What’s a decision support system? Chapter 9: Information Systems Analysis and Design Page 469

Expert Systems and Neural Networks: What is an expert system? A computer system designed to analyze data and produce a recommendation, diagnosis, or decision based on a set of facts and rules The facts and rules for an expert system are typically derived by interviewing one or more experts, and then incorporated into a knowledge base The knowledge base is stored in a computer file and can be manipulated by software called an inference engine Chapter 9: Information Systems Analysis and Design Page 470

What is an expert system? Chapter 9: Information Systems Analysis and Design Page 471

How are expert systems built? Expert systems can be created with a computer programming language or an expert system shell An expert system shell is a software tool that contains an inference engine and a user interface that provides a way to enter facts and rules Chapter 9: Information Systems Analysis and Design Page 471

Can an expert system deal with uncertainty? Using a technique called fuzzy logic, an expert system can deal with imprecise data by asking for a level of confidence Chapter 9: Information Systems Analysis and Design Page 471

Is it possible to build an expert system without an expert? An expert system begins with a set of facts and rules If the rules are not known, a computer can “learn” how to make decisions based on hundreds or thousands of lightning-fast trial and error attempts A neural network uses computer circuitry to simulate the way a brain might process information, learn, and remember Model of how we think the brain works Chapter 9: Information Systems Analysis and Design Page 471

Chapter 9 Information Systems Analysis and Design Section B: Systems Analysis 系统分析 Computer Concepts 8th Edition

Planning Phase: How does an information system project begin? An information system project begins with a planning phase The goal of these activities is to create a Project Development Plan This planning document includes: A short description of the project, including its scope A justification for the project A list of project team participants A schedule for the project, including an outline of its phases Chapter 9: Information Systems Analysis and Design Page 473

Who participates in the process of building an information system? A system development project team is a group of people who are assigned to analyze and develop an information system Other members of the organization might be asked to participate A widely accepted technique called joint application design (JAD) is based on the idea that the best information systems are designed when end users and systems analysts work together on a project as equal partners Chapter 9: Information Systems Analysis and Design Page 474

Justify Project: Why are new information systems developed? The justification for a new information system usually emerges from a serious problem with the current system, or from an opportunity to improve an organization’s products or services using technology Chapter 9: Information Systems Analysis and Design Page 474

What kinds of threats and opportunities can affect an organization? Chapter 9: Information Systems Analysis and Design Page 475

How to Identify Problems and Opportunities? Performance - response time Information - not correct information Economics - costs too much Control - (un)authorized access Efficiency - too many resourses used Services - too hard to use Chapter 9: Information Systems Analysis and Design

What is a system development life cycle? Chapter 9: Information Systems Analysis and Design Page 477

What is a system development life cycle? A system development life cycle (SDLC) is an outline of a process that helps develop successful information systems The original waterfall SDLC approaches each phase as a discrete step in the development process A modified waterfall SDLC allows overlap between SDLC phases An iterative SDLC allows phases to repeat, if necessary, as the project progresses Chapter 9: Information Systems Analysis and Design Page 477

What is a system development life cycle? Chapter 9: Information Systems Analysis and Design Page 477

How do different SDLCs affect project development? A methodology called rapid application development (RAD) proceeds with the project team creating a series of prototypes that users can evaluate Different SDLCs also affect the project schedule The tools for analyzing and designing an information system are directly related to the methodology Chapter 9: Information Systems Analysis and Design Page 478

Analysis Phase: What happens in the analysis phase? Produce a list of requirements for a new or revised information system Chapter 9: Information Systems Analysis and Design Page 478

Determine System Requirements: How does the project team determine what the new system should do? System requirements are the criteria for successfully solving the problem or problems identified in an information system They also serve as an evaluation checklist at the end of the development project Chapter 9: Information Systems Analysis and Design Page 479

How does the project team document system requirements? Chapter 9: Information Systems Analysis and Design Page 479

What marks the end of the analysis phase of the SDLC? The analysis phase concludes when the project team produces a written report that documents its findings The System Requirements Report typically contains diagrams that illustrate what the new information system should do Chapter 9: Information Systems Analysis and Design Page 480

Chapter 9 Information Systems Analysis and Design Section C: System Design 系统设计 Computer Concepts 8th Edition

Design Phase: What happens in the design phase? The project team must figure out how the new system will fulfill the requirements specified in the System Requirements Report not What Chapter 9: Information Systems Analysis and Design Page 482

Identify Potential Solutions: How does the project team come up with solutions? There might be more than one way to solve the problems The project team should identify several potential hardware and software solutions by “brainstorming” and researching case studies on Web sites and in computer magazines Chapter 9: Information Systems Analysis and Design Page 482

What hardware alternatives are available? The project team should consider the pros and cons of different levels Level of automation and computerization Processing methodology Network technology Chapter 9: Information Systems Analysis and Design Page 482

What software alternatives are available? Software alternatives include Construct the system “from scratch,” use an application development tool, or commercial software Creating an information system “from scratch” using a programming language, which can take many months or years An application development tool contains building blocks that can be assembled into a software product Chapter 9: Information Systems Analysis and Design Page 484

What software alternatives are available? Commercial software for an information system is usually a series of pre-programmed software modules A turnkey system is essentially an “information system in a box” which consists of hardware and commercial software designed to offer a complete information system solution A turnkey system must be extensively evaluated to determine whether it can satisfy system requirements Chapter 9: Information Systems Analysis and Design Page 484

How does the team choose the best solution? Chapter 9: Information Systems Analysis and Design Page 485

What’s an RFP? A document that describes the information system problem and the requirements for the solution Chapter 9: Information Systems Analysis and Design Page 486

What’s an RFQ? A request for a formal price quotation on a list of hardware and software Chapter 9: Information Systems Analysis and Design Page 486

Depends on the type of solution selected Develop Application Specifications: What happens after the project team selects a solution? Depends on the type of solution selected If the project team selected a solution that requires custom programming, the team’s systems analysts will create a set of application specifications Chapter 9: Information Systems Analysis and Design Page 487

What happens to the completed specifications? In a large information systems project, the specifications are given to a programming team or application developer who creates the software In a small information systems project, the user might develop your own specifications Chapter 9: Information Systems Analysis and Design Page 488

Obtain Approval to Implement the New System: When can the project team actually begin to build the new information system? In the design phase of the SDLC, the project team chooses a solution, selects hardware and software, and designs detailed application specifications Before the solution is implemented, the project team typically must seek approval from management Chapter 9: Information Systems Analysis and Design Page 488

Chapter 9 Information Systems Analysis and Design Section D: Implementation and Maintenance 执行及维护 Computer Concepts 8th Edition

Implementation Phase: What happens during the implementation phase? The project team supervises the tasks necessary to construct the new information system Chapter 9: Information Systems Analysis and Design Page 489

Purchase and Install Hardware and Software: Does a new information system typically require new hardware? Most new information systems require new hardware, which can either replace old equipment, or be connected to existing equipment Chapter 9: Information Systems Analysis and Design Page 489

How about new software? Many information systems require new software, such as a commercial application, a programming language, an application development tool, or an expert system shell Chapter 9: Information Systems Analysis and Design Page 489

Create Applications: What’s the next step in the implementation phase? Depends on the software tools selected for the project Software customization is the process of modifying a commercial application to reflect the needs of a particular organization Chapter 9: Information Systems Analysis and Design Page 489

What is application testing? The process of trying out various sequences of input values and checking the results to verify that the application works correctly As each application module is completed, it undergoes unit testing to ensure that it operates reliably and correctly When all modules have been completed and tested, integration testing is performed Chapter 9: Information Systems Analysis and Design Page 490

What is application testing? A test area is a place where software testing can occur When a problem is discovered during unit testing or integration testing, the team must track down the source of the problem and correct it System testing ensures that all hardware and software components work together correctly Chapter 9: Information Systems Analysis and Design Page 490

Finalize Documentation The documentation for an information system can be roughly categorized as system or user documentation System documentation describes the feature of the system User documentation describes how to interact with the system to accomplish specific tasks Chapter 9: Information Systems Analysis and Design Page 491

Train Users: How do employees learn how to use the new information system? Users need extensive training, which might include software orientation, hardware operation, data entry, and backup procedures Training sessions can be conducted by members of the team or professional trainers A procedure handbook is a type of user documentation that contains step-by-step instructions for performing a specific task Chapter 9: Information Systems Analysis and Design Page 491

Convert Data: What happens to the data from the old system? The data for a new information system might exist in card files, file folders, or an old information system When converting data from a manual system to a computer system, the data can be typed or scanned electronically into the appropriate storage media When converting data from an existing computer system to a new system, a programmer typically writes conversion software Chapter 9: Information Systems Analysis and Design Page 491

Covert to New System: How does a business switch from the old information system to the new system? System conversion refers to the process of deactivating an old information system and activating the new one A direct conversion means that the old system is completely deactivated and the new system is immediately activated A parallel conversion avoids some of the risk because the old system remains in service while some or all of the new system is activated In a phased conversion, the new system is activated one module at a time Chapter 9: Information Systems Analysis and Design Page 492

How does a business switch from the old system to the new system? A pilot conversion works well in organizations with several branches that have independent information processing systems The new information system is activated at one branch If the system works correctly at one branch, it is activated at the next branch Chapter 9: Information Systems Analysis and Design Page 492

When is the new information system formally “live”? A new or upgraded information system undergoes a final test called acceptance testing Acceptance testing is designed to verify that the new information system works as required Chapter 9: Information Systems Analysis and Design Page 492

Maintenance Phase: What happens during the maintenance phase? Involves day-to-day operation of the system, making modifications to improve performance, and correcting problems The maintenance phase of the SDLC is the most expensive because it lasts until the system is retired Chapter 9: Information Systems Analysis and Design Page 493

Who is responsible for system maintenance? The system operator performs system backups and data recovery, monitors system traffic, and troubleshoots operational problems The systems programmer is the operating system guru In an information system that is centered on a microcomputer network, a network manager or network specialist is typically responsible for day-to-day operations and system maintenance Chapter 9: Information Systems Analysis and Design Page 493

Why do maintenance activities include user support? Employees sometimes forget procedures, or have difficulty when they encounter a new set of circumstances Many organizations establish a help desk to handle end-user problems The help desk is staffed by support specialists Chapter 9: Information Systems Analysis and Design Page 494

How long does the maintenance phase last? Chapter 9: Information Systems Analysis and Design Page 495

When does the maintenance phase end? When the information system is no longer cost effective, or until changes in the organization make the information system obsolete Chapter 9: Information Systems Analysis and Design Page 495

Conclusion You should now be able to: Describe how information systems help organizations fulfill their missions, deal with threats, and take advantage of opportunities Contrast and compare the characteristics of transaction processing systems, management information systems, decision support systems, and expert systems Apply the PIECES framework to classify problems that reduce the effectiveness of an information system Chapter 9: Information Systems Analysis and Design

Conclusion Describe various models for the system development life cycle (SDLC), and explain the focus of the structured, information engineering, object-oriented, and rapid application development approaches to system development List the activities that take place in each phase of the system development life cycle Describe alternative hardware and software solutions that a project team might consider Chapter 9: Information Systems Analysis and Design

Conclusion Explain the differences between unit testing, integration testing, system testing, and acceptance testing Describe the advantages and disadvantages of direct, parallel, phased, and pilot conversion techniques Explain how user feedback helps system operators identify and fix “bugs” Chapter 9: Information Systems Analysis and Design